Almost on every mission the astronauts did some digging, but how deep did they reach? According to this article:

The regolith is generally from 4 to 5 metres thick in mare areas and
from 10 to 15 metres in the older highland regions.[3] Below this true
regolith is a region of blocky and fractured bedrock created by larger
impacts, which is often referred to as the "megaregolith".